I've been playing that characters can't move through opposing players, unless that opponent is prohibited from attacking them.

This allows a player to block a labyrinth, forcing at least one round of melee. We have been allowing players to move on, exiting melee, running away as it were from the fight. I haven't found a prohibition to this, am I just missing it?

I've been playing that characters can't move through opposing players, unless that opponent is prohibited from attacking them.

Incorrect. You have to stop on an enemy character. You may or may not melee but you have to stop. Some characters allow you to move through. (For reference it's Masters Addendum p.10)

Quote:

This allows a player to block a labyrinth, forcing at least one round of melee. We have been allowing players to move on, exiting melee, running away as it were from the fight. I haven't found a prohibition to this, am I just missing it?

Correct. There is nothing to prohibit you leaving a hex with an enemy. (Unless there is some power or something, but I don't recall one).

I've been playing that characters can't move through opposing players, unless that opponent is prohibited from attacking them.

This allows a player to block a labyrinth, forcing at least one round of melee. We have been allowing players to move on, exiting melee, running away as it were from the fight. I haven't found a prohibition to this, am I just missing it?

You have this all correct. I think that the previous poster misread your post.

Characters must stop when entering a space with a potentially aggressive enemy, no matter how unlikely the possibility of an actual attack. If the enemy character is forbidden from attacking due to a special ability or other effect, then passage is allowed.

You are always allowed to leave a melee hex during your movement unless you entered the hex during the same movement phase.

This allows a player to block a labyrinth, forcing at least one round of melee. We have been allowing players to move on, exiting melee, running away as it were from the fight. I haven't found a prohibition to this, am I just missing it?

You can block the labyrinth, make the opponent stop, then move one space on your turn, blocking the labyrinth again, so the opponent moves one space and has to stop again, and so on.